When people hear the term MIDI, they often associate it with poor-sounding computer music files from the eighties and nineties. But if you've recorded something on a computer or mobile device recently, you may know it's not the entire story—or even all that accurate. MIDI—short for Musical Instrument Digital Interface—is a protocol designed to let computers talk to musical instruments.

First unveiled in 1983, and maintained by the MIDI Manufacturers Association to this day, the royalty-free MIDI protocol remains as one of the only genuine technical collaborations between electronics vendors that normally compete with each other, such as Roland, Korg, and Yamaha. It's probably the most significant development in synthesizers since the original Moog synth. It's still the primary way composers write scores for major motion pictures, TV shows, and video games, and if you've used Pro Tools, GarageBand, or another recording program, you've probably used it too.

It's All About Numbers
How MIDI works is really simple. Let's say you play a note on a MIDI-compatible keyboard. That action generates data containing which note it is (A, C, or D, for example), how hard you press the key, how long you hold the note, and other relevant info, mostly based on a number scale from 0 to 127. A MIDI stream also contains other information, such as data for sustain pedals on a piano, breath controllers on an electronic wind instrument, or electronic drum pad triggers, to name just three examples. Computer software can interpret this data and show it in easily digestible lanes for each instrument, as well as piano roll-style editing or even sheet music-style notation views, such as in MOTU Digital Performer (pictured, above left).

The amount of data transmitted is tiny by current standards—a few hundred kilobytes at most. But the development of MIDI, with the first products released later in 1983, had tremendous implications for the music industry. MIDI enabled the first computer sequencers, and hardware sequencers for that matter, to control one or more musical instruments, and record performances in a way that let you easily edit them after the fact. MIDI also gave birth to rack-mount modules, which were synthesizers without the actual piano-style key bed, and resulting size and weight that comes with that.

In addition, MIDI helped launch the PC game industry, thanks to the array of soundcards that appeared on the scene beginning in 1989. Back then, before the age of the CD-ROM games and digital music files, you simply couldn't cram a full digital soundtrack onto 3.5-inch floppy disks. MIDI let composers write complete soundtracks for computer games—and even enabled the beginnings of adaptive music, which let developers create music that adapts to gameplay in real time, instead of linear music that works fine for movies but gets repetitive quickly as the player spends a long time in one room or level of the game.

Digital Recording Made Easy

Throughout the early nineties, the flawed General MIDI standard made it easy to pass music files back and forth, without having to reassign each instrument track to a new sound. Unfortunately, General MIDI is what gave MIDI music its bad reputation. Download and cue up a .mid file from the Web, and you'll hear a dinky rendition of the appropriate song. That's not because MIDI sucks—it's because the dinky instrument sets built into QuickTime, Windows Media Player, and other programs suck. Some of the cheaper soundcards popular from that time also had weak instrument sets. And none of these files are properly mixed or mastered with any EQ, compression, or other tools.

The thing is, MIDI permeates the entire music industry even today. It makes possible the latest, amazing-sounding virtual instruments, with hundreds of gigabytes of samples. To this day, most commercial music composers mock up their tracks using MIDI, with only the biggest-budget blockbusters getting the chance to hire an orchestra to play the score live after the fact. And the racks of synthesizers and modules commonly seen in studios for decades have largely given way to software instruments, often driven by inexpensive MIDI controller keyboards like the M-Audio Axiom Air (pictured above) without any built in sounds of their own. It makes it possible for, say, a singer-songwriter working at home to put together backing bass guitar, drum, and keyboard tracks, and then play her guitar and sing over them to complete finished songs.

Unfortunately, we've never really seen this same level of technical collaboration between manufacturers since. Music files (MP3, AAC, WMA), movie discs (Blu-ray, HD DVD), audio recording standards (ADAT, DA-88, countless plug-in formats)—virtually every key format of the past 30 years has suffered at the hands of creators attempting to secure royalties from it. The future of music technology may be subject to continued competition, but that also drives technology forward, so it's largely a good thing. It's a shame, though, that manufacturers don't work together just a bit more often to advance the state of the art—especially when it could benefit them so much. As the cliché goes, a rising tide lifts all boats.